phy: tegra: Print -EPROBE_DEFER error message at debug level

Probe deferral is an expected error condition that will usually be
recovered from. Print such error messages at debug level to make them
available for diagnostic purposes when building with debugging enabled
and hide them otherwise to not spam the kernel log with them.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/phy/tegra/xusb.c

@@ -1174,7 +1174,13 @@ static int tegra_xusb_padctl_probe(struct platform_device *pdev)
 
 	err = tegra_xusb_setup_ports(padctl);
 	if (err) {
-		dev_err(&pdev->dev, "failed to setup XUSB ports: %d\n", err);
+		const char *level = KERN_ERR;
+
+		if (err == -EPROBE_DEFER)
+			level = KERN_DEBUG;
+
+		dev_printk(level, &pdev->dev,
+			   dev_fmt("failed to setup XUSB ports: %d\n"), err);
 		goto remove_pads;
 	}